Heretofore, it has been well known that the edgewise orthodontic technique preferably requires an archwire to be attached to a tooth by securely placing the archwire in the mesial-distal archwire slot of a twin edgewise orthodontic bracket. The most common method for securing the archwire in the archwire slot has been by ligating an elastic ligature around the tie wings of the bracket and over the archwire at the mesial and distal sides of the bracket. While this method securely holds the archwire in place, it causes significant friction between the archwire and the bracket, thereby requiring greater forces to move teeth. Further, the ligatures need to be replaced quite often when they break, deteriorate, or when the archwire is changed. During treatment, the archwire may be changed many times. The process of constantly ligating each bracket with each change of the archwire greatly increases patient chair time. Additionally, elastic ligatures attract contaminating substances that increase the chances for the transmission of disease and decrease overall oral hygiene.
Due to these problems, numerous brackets have been created which include engagement mechanisms for retaining the archwire. For instance, U.S. Pat. Nos. 4,144,642; 4,248,588; 4,698,017; 3,772,787; 4,786,252; 4,559,012; 4,561,844; 4,655,708; 4,077,126; 4,419,078; 4,634,662 and 4,197,642 illustrate various designs for such brackets. However, while some of the bracket designs contemplate twin edgewise brackets, none have the structure, function, and reliability desired by the clinician.